Job speed dating as such isn´t new. They do it in real for school graduates where I live. To do it online fits the target group, I admit. But why announce it in a classic way via billboards? And how exactly do you combine the questionnaire with a (viral?) car race. Some good approaches here, but to me this whole concept isn´t matured yet...

Never claimed Job-Speed-Dating is new. ;-) BUT a job-speed-dating-online-car-racing-game is! A speed-dating-job-interview in a formular 1 car and the resulting viral clip is new as well. Or have you heard about it? "New things" happen often when you put existing things together in a new way. The billboard is one little detail of the concept to promote the game. AND it's not just a common billboard Janne. It's one part of the flag-waving guerilla. Details matter!
As you see, there are more activities to promote the game: Guerilla Pit-Stops and (as i commented under MKaminski's comment) promotion on dating platforms and job-platforms.

Don't understand your question "how exactly do you combine the questionnaire with a (viral?) car race." The car-racing-job-interview will promote the online-car-racing-game. As simple as that.

Still some more things to refine. Ok. But that's the same for others here. ;-)

Hi voto, just a hint for promotion, maybe you could already give people a glance of what it feels like, by allowing them to do a little speedy race within an other banner, using a smartphone as a remote or so. It might not be attractive for all potential candidates, but for sure techies will love a try,... just an idea,... keep it up

See the clip at the and of my presentation. I will add an english version soon. The idea is:

The claim of mobile.de, that should be integrated into the job campaign concept is "Which one is your next one?" They talk about cars. I use the same claim in the context of "partnership" to raise attention for the "speed dating car racing game". Speed dating originally comes from partner search. I propose a banner campaign on dating websites with the following text idea:

"Your old one is history?"
"Now it's your turn!"
"Which one is your next one?" (Button: "Find him know")

There is no campaign reaching ALL potential candidates. ;-) The concept consits of serveral on- and offline activities not just the game and it won't be mandatory to join the game if you like to apply for a job. You can send your job application in the traditional way too.